Considerable attention has been given to the problems of Laguna de Bay concerning aquaculture and environment. It is a large lake adjacent to metropolitan Manila. Of its 90 000 hectares, over 5 000 hectares are devoted to the cultivation of milkfish or bañgus (Chanos chanos) in fishpens (Delmando and Gedney, 1974; Felix, 1973, 1974). Laguna de Bay is subject to the stress of urbanization and agricultural run-offs resulting in eutrophic and polluted conditions.
During mid 1975 the fishpen operators suffered a 2.8 million peso* fishkill. This fishkill was due to the culmination of many factors, some of them intrinsic to the lake itself and others from introduced sources (run-offs, overcrowding of stock, etc.). No one factor has been deemed responsible. Oxygen depletion was probably the actual biggest direct killer but could have acted together with other synergistic agents, i.e. toxic algal by-products, metabolic stimulations, etc., plus the actual causative mechanisms that resulted in low oxygen with this unique lake were not understood. In any lake of this size, subject to the unusual stresses brought on by surrounding technological improvements, there is an extremely complex environmental profile that will continue to change with the passage of time.
SCSP has conferred with various government agencies that are investigating the lake's various characteristics. Not only is the lake important from a fishery standpoint (LLDA, 1975) but it is also being considered as the main source of drinking water for Manila in the future (Sogreah, 1974).
The Bureau of Fisheries and Aquatic Resources (BFAR) has been conducting investigations in Laguna de Bay many years. In recent years the Laguna Lake Development Authority (LLDA) has conducted water quality studies (Lee, 1975). In addition, the National Science Development Board (NSDB) has conducted investigations and recently attempted to coordinate research activities. Tentative studies by LLDA and referred to Asian Development Bank (ADB) for funding are planned to determine the feasibility of increasing the fishpen culture from 5 000 to 20 000 hectares, or over 20 percent of the total lake. Many conferences were held with these agencies concerning the lake's future development.
* Philippine currency is based on the Peso (
); 7.50 is equivalent
to U.S. $1 as of April 1976.
The writer feels that Laguna de Bay is a delicately balanced body of water and continued stress is being placed on it by expanding urbanization (Barica, 1976). It has received a great deal of attention because of its proximity to metropolitan Manila.
Insofar as the general pollution of the Philippines is concerned it is similar to other Asian countries. Run-offs from 20 mines to seven rivers account for most of the coastal siltation. The majority of these mines produce copper, gold, silver, iron and chromite related tailings. Siltation is estimated at 60 million tons per year. This siltation problem is limited to well-defined areas and is not a serious problem along the entire coast of the Philippines.
Thermal pollution from six thermal plants is mostly limited to inland areas and does not affect the coastal regions directly. Small scale thermal pollution is also coupled with mill discharges.
Two nuclear power plants are expected to be established in 1980–1990 which may change thermal patterns in the future.
Most of the information available on all types of pollution from the Philippines concerns Manila and adjacent areas. Most pollution studies have been carried out in these areas, because of the pollution concentration in Manila, and the difficulties in conducting systematic information surveys in other areas. Manila (pop. 4 500 000) is 12–15 percent sewered; however, untreated sewage is discharged into Manila Bay. Manila Bay's average is 1000/100 ml coliform with a very wide range; 2 000 000/100 ml along shore to 200/100 ml in the centre of the Bay. Domestic sewage produces 290 tons BOD and 350 tons of total solid wastes, based on figures of 54 g/capita/day or 20 kg/capita/year, while 120 industrial firms contribute 26 tons BOD and 114 tons in total solids to Manila Bay. Within one or two years factories are expected to have their own treatment systems.
At present, there are almost 28 sugar centrals and refineries and 10 distilleries throughout the country. Eleven of these refineries and 4 distilleries are concentrated in Negros island.
Pulp and papermills are next in the order of pollution sources. There are six integrated pulp and paper mills and twenty four paper mills whose wastes affect in one way or another the coastal waters of the country today, causing damage to 17 river systems. The most adversely affected operator of aquatic industries by this type of waste are aquaculture operators and coastal fishermen. Most of their fishery projects are at estuaries. Fishpond owners have complained of a 50 percent reduction in harvest rate in affected areas.
Pesticides as well as fertilizers are used extensively to increase rice production. Likewise, insecticides are used extensively in all forms of aquaculture. These toxic chemicals are carried by surface run-offs into rivers and streams, and finally into the sea. Fish life in coastal areas can be affected by the toxic effects of pesticides, particularly the chlorinated hydrocarbons. However, the amounts of pesticides used in the country were not obtained.
There is at present a concentrated effort to investigate the levels of every kind of pesticide in waters along the coast of Manila Bay and in aquatic living resources. The country has ongoing investigational projects being undertaken by twenty-four fixed stations using samples of waters and fish for chemical analysis once a month.
In the reply to Questionnaire issued by FAO/IOC before a workshop on marine pollution in east asian waters, levels of pesticides are only shown to be less than 0.5 ppb in sea waters but more detailed results of the investigation in Manila Bay is presented in the national report.
Nationwide surveys of mercury and other heavy metals in waters, sediments and biological samples have been carried out, specially by three stations in Manila Bay and at stations in Palawan island (Puerto Princesa), and Bislig Bay in Mindanao island. Observed levels of mercury were also recorded to be less than 1 ppb in water and less than 0.1 ppm in biota.
There are no major oil pollution problems reported in the Philippines. In and around Manila Bay occasional oil slicks are encountered. It has been predicted that under certain monsoon conditions oil spills from the oilfields off the west coast of Borneo, could enter the Sulu Sea and reach the shores of Palawan, Mindoro and Luzon.
During the first of March 1976 one commercially valuable well was identified off Palawan.
The Project Summary for the proposal - Programme of Prevention and Control of Water Pollution for the Protection of Living Coastal Resources - is in Appendix II of this report. Physical pollution in Thailand is categorized into the following areas:
Sediment from erosion in the amount of 1.5 × 106 tons/year is concentrated at the mouth of the major river systems, emptying into the Northern Gulf of Thailand which has resulted in a vast delta (3 695 km2) in the Gulf of Thailand. Reforestation has not been actively engaged in at the present time;
Siltation on coral reefs in the area of Phuket and other areas takes place because of extensive tin mining.
Also, thermal addition comes from electricity production and sugar mills in the industrialized areas of southern Thailand. Two atomic power plants with a total capacity of 1 200 MW are expected to be established in the next three years. Plastic products constitute a dumping hazard.
Bangkok with a population of about 4 million has no sewage treatment plants (1972), and together with towns to the north along the main rivers, produces 50 × 106 kg/year BOD.
The deficiency of dissolved oxygen in major rivers is a problem to fisheries. A combination of raw domestic sewage and food related industrial wastes produce DO's (dissolved oxygen) in these rivers of less than 2 ppm 50 percent of the time. At certain times, the DO is zero.
The maze of klongs (dead-end canals) act as sort of large septic tanks which are periodically dug out.
In general there are no treatment plants for industrial waste at the present time, however, the government is planning to remedy this in the near future. The implementation of treatment facilities is difficult because of the large number of small scattered industries that add organic and other forms of wastes to rivers and coastal areas. Many individual fish meal, canning, and food processing types of plants contribute to the BOD load. One sugar mill produced a BOD equivalent to 100 000 inhabitants. Some of the obvious polluters are pulp mills discharging highly toxic black liquor into rivers.
Pollution from various sources is so highly concentrated that it does enter the northern coastal waters, 50 km from Bangkok, and has affected fisheries as shown by sea mussel harvest, which in 1971 was 214 593 kg but in 1974 was 13 044 kg. This decline has been traced directly to water quality. Most forms of pesticides are used in Thailand and in the near future some useful information will be forthcoming from universities and government agencies.
In a recent study (Menasvata, 1976) traces of mercury were found in the marine food chain which tend to increase at higher levels of the food chain and according to animal size. However, limits were found to be within normal ranges and not caused by pollution.
Oil pollution in Thailand is not a problem at present except at scattered resort beaches south of Bangkok or on beaches of Phuket island.
The consultant did not have time to visit Hong Kong, Indonesia, Malaysia and Singapore but there were some information made available to him during this consultancy. These are summarized below.
Hong Kong's major source of pollutants stems from the massive Pearl River which originates on the China mainland and has a major influence on the western and southwestern waters of Hong Kong.
Reclamation projects in Hong Kong are of importance to the economy. The present waterfront of Kowloon and the northern shore of Victoria island consist almost entirely of reclaimed land.
Hong Kong's sewage is discharged raw into the sea without any pretreatment except the removal of screenable material from larger discharges. Sewage from the central areas of Hong Kong island and Kowloon, which has 3.40 million of the total population of 4.16 millions (1971 figures), is discharged into Victoria harbour. Hong Kong has a considerable garbage problem, which is not merely an aesthetic nuisance but also a real hazard to navigation. Floating garbage is collected by the Marine Department of the Hong Kong Government from Victoria harbour, a total of 6 930 tons being gathered in the year ending 31 August 1973. Drifting garbage is also found on many beaches.
Based on data supplied to the consultant, a BOD of 47 g/capita/day or 17 kg/capita/year has been calculated for sewage and 36.3 g/capita/day or 13 kg/ capita/year for night soil. In the sediments 40–700 mg/l BOD were found.
There are commercial oyster beds located in Deep Bay on the northwestern coast of Hong Kong, which are estuarine in character because of both local runoff and the proximity of the Pearl river originating on the mainland. Oysters are cultured by bottom laying and the annual catch, which fluctuates widely, has declined from a peak of 1 494.1 metric tons (value US$350 000) in 1957–58 to 160 metric tons (value US$394 000) 1970–71. It has been reported that the oysters are grossly contaminated by faecal bacteria. But other problems such as inefficient culture techniques and labour shortage have probably contributed also to the decline.
No outbreaks of diseases have been reported amongst consumers, but this is an area of active concern. Counts of coliform bacteria are very high in Hong Kong waters, value of 1000 per 100 ml being common, and frequent high counts of 10 000 per 100 ml have been recorded.
Another problem is the effluents from industries. It was found that the textile bleaching and dyeing industry accounted for some 88 percent of industrial water consumption. It therefore appeared that this industry was the most important source of industrial effluents, producing strongly-coloured and predominantly alkaline wastes with a mean chemical oxygen demand (COD) of 1 335 mg/1. Total water consumption was estimated at about 225 000 m3/day for the whole industry, contributing a volume of waste water which is roughly equivalent to that produced by one million people. Domestic animal waste problem is present too as in Singapore.
Oil pollution is due mainly to accidental spillage or collisions. In the past, mariculture cage projects have suffered from some diesel oil spillage.
This country has the longest coast line of all the SCS countries due to the myriads of islets and islands included within its boundaries.
Soil erosion occurs mainly on the island of Java due to its high population density of more than 500 inhabitants/km2. This has caused a “delta” build up along the northern coast.
Sumatra and Kalimantan have siltation problems too, however this soil erosion is due mainly to deforestation associated with the lumber industry.
Mining, especially tin, is an important industry in Indonesia. East of Sumatra (Bangka, Belitung and Singkep islands), siltation due to tin mining is increasing because it is partly exploited by the use of offshore dredging. In 1973 there were 22 500 metric tons of tin concentrate produced. This type of siltation is felt by the immediate coastal areas which consists mainly of mangroves. The coast of Indonesia especially near Jakarta has also been damaged by the taking of sand and coral rocks for the construction industry.
Thermal addition does exist but is still relatively small. By the year 2 000, it is planned to have the following power plants functional:
| Kind of generation | Power ('000 MW) |
| Hydro-power | 4–5 |
| Oil | 12.8–39 |
| Geothermal (Volcanic system) | 0.5–6 |
| Coal | 8–16 |
| Nuclear | 15–25 |
There are large cities along the coast, i.e., Jakarta -5.1 × 106 (1973), Surabaja -1.5 × 106, Semarang - 1.1 × 106 plus the dense population of Java as a whole is greater than 500/km2. There are no treatment facilities at all which results in high bacterial contamination to onshore waters.
Industrial impact is starting to be felt but is quite difficult to assess. There are a number of government agencies beginning to accumulate information on industries such as papermills, textile and detergent manufacturs.
The Malaysian coasts are predisposed to the effects of oil spillage. In 1973 some 4 300 loaded oil tankers passed through the Straits of Malacca carrying oil cargo exceeding 300 million tons which constituted 12 percent of the maritime traffic through the Straits. Two consequential oil spills have recently occurred i.e., “Showa Maru” grounded in the southern tip of the Straits of Malacca in January 1975 and the “Tolo Sea” grounded near Penang in August 1975.
The pesticides used in the country include DDT, dieldrin, endrin, abate, BHC, endosulfan, malathion and sodium arsenite. Only the quantities of imported sodium arsenite are known which was 13.9 tons in 1973. One serious effect of pollution leading to the deterioration of spawning grounds is the disappearance of the herring species of Hilsa macrura from the Straits of Malacca. Trace metals (copper, zinc) are being studied in fish and plankton but little research is being done on pesticide residues in aquatic organisms.
Domestic sewage and industrial wastes come from population centres and scattered industrial plants. The Straits of Johore and waters near Penang island feel most the impact of organic wastes as shown by highest coliform counts in these vicinities (18 000/100 ml) compared to 500/100 ml in least populous areas. The established industrial plants like pineapple canneries, flour mills, fish processing and meal plants have been producing oxygen-consuming wastes for sometime and agro-based industries such as rubber and palm oil are affecting some of the rivers.
Singapore is an island state with a limited area and a population of about 2 200 000. There are two sewage treatment plants (1969); one discharging by pipeline into an estuary in the Johore Strait and the other into a small river. These two plants are not capable of treating all the sewage (1973) so some raw sewage is also discharged. No information is available concerning industrial organic waste.
Singapore now produces 75 to 80 percent of its pork and poultry supply with its standing stock and poultry population. This animal population produces daily 14 m3 pig slurry and 560 tons of poultry wastes which poses disposal problems.
